Abstract
Background/Aims Early life factors such as birth weight have been found to be associated with risk for child overweight. Birth size measures such as birth length and various weight for length indices, and gestational age may also be related to the risk for later adiposity, but the contribution of these other variables is still unclear. We examined the role of birth size and gestational age with BMI in children at ages of approximately 5 years old in a multiethnic population.
Methods This is a retrospective, longitudinal study that used Kaiser Permanente Hawaii Electronic Medical Record (EMR) data of 1720 children born in 2004 and 2005. We examined birth weight (kg), birth length (cm), gestational age(wks), and birth weight for length indices (weight divided by length, by length^2 (BMI) or by length^3 (ponderal index)) as indicators of birth size measures. The clinic visit weights and heights closest to age 5 y were used calculate BMI (kg/m^2). Multiple regression models of BMI at age 5y included gestational age and either birth weight or a function of weight and birth length.
Results Birth weight was associated with BMI at age 5 y (ß = 0.99, SE = 0.12, p = 0.0001). Gestational age was independently (and inversely) associated with BMI at age 5 y (ß = −0.12, SE = 0.03, p = 0.0001), but it did not affect the association between birth weight and BMI. Birth length was not independently associated with BMI and the interaction with birth weight was not statistically significant. Separate models of birth weight to length indices adjusted for gestational age, account for less of the variance in BMI at age 5y than models with birth weight.
Conclusion Birth weight and gestational age are independently associated with BMI at age 5y. However birth length and indices of birth weight for length were not associated with BMI at age 5y. Thus, there is potential for birth weight and gestational age to serve as risk indicators of increased BMI at age 5y.
